Sounds like a great feature. Elsewhere in this thread I asked for advice on how could I take two mp3 recordings and synchronize their tempos and beats but couldn't get a very clear answer, except that it is a "very basic task".
Reading your comment about this new feature it seems obvious to me now that if the tempos in those mp3 recordings vary independently, like they do in much recorded music, it would be impossible to sync the tracks without this new feature. Right?
Not quite. I think we're discussing two different things. You're trying to synchronize two pre-recorded songs. That feature has been around since the beginning and is fairly trivial to do once you learn some of Ableton's core concepts. That can be demonstrated in countless Youtube videos.
What I'm describing is composing music on the fly that is locked to a master tempo and clock (like most electronic music). Jamming with another musician and staying in sync is easy if they're also using drum machines or other hardware that can clock off the same source. What Ableton's new Tempo Follow feature does is allow the DAW to listen to the audio of live musicians (say a Jazz quartet) and then automatically speed up and slow in real time when they choose to. Now, when the band pushes the tempo my sequenced instruments wont lag behind the beat and get out of sync.
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I think what you're trying to do is synchronize the tempos of two songs that both push and pull their tempos a bit. That involves compromise and maybe some automation. Let's use an example of two different kinds of songs which we'll call 1) rigid songs and 2) loose songs.
Rigid songs are like house music or techno. They're clocked exactly to a given tempo that doesn't waver throughout the song unless the composer automates it. This is common in electronic and modern pop music. These are the easiest to synchronize because they don't have any tempo variations and require far less work to tempo match. Loose songs are songs that have subtle or dramatic tempo changes: Jazz, old rock and roll records, or classical music (which usually has a lot of rubato).
What I believe you're asking about is trying to sync two loose songs or a loose song and a rigid song. Well the short answer is that you'll likely have to compromise a bit. Let's say a Led Zeppelin song hovers around 80bpm. At some points the band slows down to 78bpm and other times they push the tempo up to 84bpm before ultimately settling back to a mean tempo of 80bpm. Well if you wanted to synchronize the Zeppelin song with a rigid song you can set the Segment BPM (What you're designating as the average tempo in Clip View) to 80bpm for the Zeppelin song and then use warp markers to snap the song to the 80bpm grid in the parts where the band pushes or pulls against the tempo and deviates from the grid.
At this point you might point out that manually aligning the audio file strictly to the grid compromises the emotional excitement and groove of the Zeppelin song by quantizing the tempo. You'd be absolutely right. It really comes down to what your intention is and how much you're willing to sacrifice that quality for the sake of making two songs synchronize. Preserving that feel then becomes more of an art and involves careful adjustment of the warp markers and using your ear to gauge the results. Often the more musically exciting choice is one that doesn't adhere strictly to a grid.
It also comes down the content of the songs. Without audio examples it's hard to be too specific about what choices should be made.
Yes much thanks. But so to do the tempo-syncing you say I need to "use warp markers to snap the song to the 80bpm grid ...". I would have hoped that this could be done automatically (with the new feature in the new version perhaps).
If it can synchronize with live musicians, would it not be as easy (or even easier) for it to synchronize with a recording of live-musicians?
Reading your comment about this new feature it seems obvious to me now that if the tempos in those mp3 recordings vary independently, like they do in much recorded music, it would be impossible to sync the tracks without this new feature. Right?